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Male behaviour during breeding season

Male behaviour during breeding season


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The mountain blue bird build nests to attract females and exhibit aggression towards other males during breeding season. Which of the following is likely to give the birds maximal evolutionary fitness?

a) stronger aggressive behaviour only during egg laying

b) stronger aggressive behaviour during nest building rather than during hatching of eggs

c) stronger aggression when egg is first laid than during nest building

d) greater aggression during hatching eggs than during nest building


a) stronger aggressive behaviour only during egg laying

c) stronger aggression when egg is first laid than during nest building

d) greater aggression during hatching eggs than during nest building

These all occur after the stage which determines fitness. Egg laying (a and c) and Egg hatching (d) occur after the male has won the right to mate.

b) stronger aggressive behaviour during nest building rather than during hatching of eggs

Assuming the behavior increases mating success and fitness, the answer is B because this is the only strategy that attracts more females and gets rid of rival males before it is too late (i.e. before the female mates). This is also assuming that the female can/will only mate once.

In chronological order the answers run "B,C/A,D" (C & A are really one and the same in my eyes). Mating occurs between B and C.


Male behavior through the breeding season in Saimiri boliviensis boliviensis

The Bolivian squirrel monkey (Saimiri boliviensis boliviensis) is a seasonal breeder. Male squirrel monkeys show distinct morphological and behavioral changes prior to and during the breeding season. A “fatting syndrome” includes increased body weight, increased levels of androgens, and in the Bolivian subspecies, an increasingly active role in the social organization of the group. In this study, the behavior of ten adult male Bolivian squirrel monkeys was analyzed over a 6‐month period prior to, during, and after the breeding season. Each was housed as the only adult male in a breeding unit with six to ten adult females and one juvenile male. Employing a principle components method, 11 behavioral clusters were generated from 27 responses. Their activity clusters were identified as follows: sexual activity that showed a peak around the time of peak conceptions excitatory activity that was initially high but decreased throughout the breeding season and maintenance activity that did not change across the breeding season. The changing social behavior of the male squirrel monkey parallels physiological changes and is correlated with changing androgen levels.


Breeding and aggressive behavior among males in a colony of Nyctinomops laticaudatus (Chiroptera: Molossidae) in Mexico

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Research output : Contribution to journal › Article › peer-review

T1 - Breeding and aggressive behavior among males in a colony of Nyctinomops laticaudatus (Chiroptera: Molossidae) in Mexico

AU - Martínez-Rodríguez, José L.

N2 - In the archeological site of Uxmal, Yucatan, Mexico, Nyctinomops laticaudatus roosts in mix groups (males and females) of bats. We studied intrasexual male aggression in relation with the position of the bats in the groups permanent males had the higher number of aggressive behaviours toward temporary and subadult males. Aggressive behaviour was more common when bats were further packed on the roosting site, and was significant higher during the breeding season compared with the non-breeding season. Females do not have a sexual preference correlated with the agonistic behaviour displayed by the males. Mate guarding was observed a few days before female acceded to copulate. Rejections by females were more common during the guarding period than during the receptive period. Copulation rate was similar for resident and temporary males. © SAREM, 2011.

AB - In the archeological site of Uxmal, Yucatan, Mexico, Nyctinomops laticaudatus roosts in mix groups (males and females) of bats. We studied intrasexual male aggression in relation with the position of the bats in the groups permanent males had the higher number of aggressive behaviours toward temporary and subadult males. Aggressive behaviour was more common when bats were further packed on the roosting site, and was significant higher during the breeding season compared with the non-breeding season. Females do not have a sexual preference correlated with the agonistic behaviour displayed by the males. Mate guarding was observed a few days before female acceded to copulate. Rejections by females were more common during the guarding period than during the receptive period. Copulation rate was similar for resident and temporary males. © SAREM, 2011.


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In: Journal of Zoology , Vol. 266, No. 2, 01.06.2005, p. 197-204.

Research output : Contribution to journal › Article › peer-review

T1 - Sexual differences in behaviour during the breeding season in the soldier crab (Mictyris brevidactylus)

N2 - The soldier crab Mictyris brevidactylus breeds in winter. Large females spawned over a few days in early winter after most had decalcified their vulvar opercula. Some females spawned in their first winter, less than 1 year after settlement. The crabs probably copulate during a few days before spawning while the vulvar opercula are decalcified. During the daytime low tide in the breeding season, large males emerged and fed on the sediment surface. Females, on the other hand, made a sand roof above themselves using sand pellets from which they had sorted out food particles, and they fed while hiding under it. After the males had ceased their surface activities, they entered the sand tunnel made by the female. The roof was connected with a hollow shaft, which had been made when the crab had ascended to the surface. Before the habitat was submerged, the shaft was plugged from within with sand to form an air chamber, which suggests that the male and female descend together in the air chamber and copulate there. It is possible that the crab uses the sand roof as a visible signal to attract mates.

AB - The soldier crab Mictyris brevidactylus breeds in winter. Large females spawned over a few days in early winter after most had decalcified their vulvar opercula. Some females spawned in their first winter, less than 1 year after settlement. The crabs probably copulate during a few days before spawning while the vulvar opercula are decalcified. During the daytime low tide in the breeding season, large males emerged and fed on the sediment surface. Females, on the other hand, made a sand roof above themselves using sand pellets from which they had sorted out food particles, and they fed while hiding under it. After the males had ceased their surface activities, they entered the sand tunnel made by the female. The roof was connected with a hollow shaft, which had been made when the crab had ascended to the surface. Before the habitat was submerged, the shaft was plugged from within with sand to form an air chamber, which suggests that the male and female descend together in the air chamber and copulate there. It is possible that the crab uses the sand roof as a visible signal to attract mates.


Dissociation of testosterone and aggressive behavior during the breeding season in male chestnut-collared longspurs, Calcarius ornatus

In many species of birds, expression of male-male aggression during breeding elicits increased secretion of testosterone. Elevations in testosterone in turn enhance expression of aggressive behavior in appropriate contexts. However, in other species, the relationship between elevated plasma testosterone and aggressive behavior is subtle or nonexistent. We examined the relationship between high testosterone and male-male aggression in the chestnut-collared longspur, a species in which males exhibit a peak in testosterone early in the breeding season that declines to a breeding baseline after nests are initiated. Elevated testosterone enhances sexual behavior after nests are initiated, but does not affect care of nestlings. We used simulated territorial intrusions (STIs) to test (1) if males increased testosterone secretion after an aggressive interaction early in the breeding season (2) if expression of aggressive behavior declined as testosterone levels declined to the breeding baseline, and (3) if experimentally elevated testosterone enhanced aggression when testosterone levels were at the breeding baseline. Plasma testosterone was unrelated to duration of STI before nests were initiated. In addition, although males were significantly more aggression prior to nest initiation than during incubation, elevation of plasma testosterone to pre-nesting levels did not enhance aggression during incubation. Thus, although elevated plasma testosterone and expression of aggressive behavior appear to overlap temporally, high plasma testosterone and male-male aggression may not be fully coupled in this species. We suggest that high plasma testosterone may be more important in eliciting and maintaining sexual behavior than aggressive behavior in this species.


Mating Season for Each Deer

Seasonal changes trigger deer’s mating cycles. Deer have instinctual abilities to recognize changes in temperature and day length.

However, there are different breeding seasons for each species of deer.

Whitetail Deer

White Tailed Deer are polyestrous, which means females can be in heat more than once per year. In the most northern reaches of the whitetail range (United States into Canada), females go into heat during November and lasts over 24-hour cycles. However, the whole whitetail mating season is from October to December.

In more southerly climates in South America, whitetails will not be ready to mate until January or February. When a doe is not mated during the first cycle she enters a second estrus period about a month after the first. Whitetail fawns are born in late spring after a near 200-day gestation period.

Red Deer

Red Deer are one of the most widespread deer species. Populations are found in Europe, the Americas, and Africa. Males and females will never interact outside of mating season, since red deer are solitary animals most of the year.

During October, the breeding season brings the opposite sexes together. Famously red deer males do not use antlers to battle during the rut. Instead, they use a roar to attract females, with lower roars gain the female’s affection. Fawns conceived during breeding season will be born in late spring.

Mule Deer

Mule Deer roam the western parts of the United States, including some of the most arid desert regions. They react differently to more subtle seasonal changes as polyestrous and short-day breeders. Peak mating season for mule deer is during November and December.

Mating itself can take several days. The buck and doe spend the time in ritual chase games, remaining together for a short time after mating. Fawns are born after seven months, in late spring and early summer. First-time mothers will birth a single fawn initially, then twins in following years.

Reindeer

Reindeer live in cold climates across the Arctic. Breeding season begins in the first weeks of September and lasts up to a month. Some reindeer located in the harshest climates will start breeding earlier (in August) to ensure nutritional peak in areas where food is scarcer.

Gestation lasts around seven months. Reindeer have perhaps the most famous use of velvet on their antlers to protect and help them grow strong.

Roe Deer

Roe Deer are a European species mostly found in Scotland and the United Kingdom. They begin their mating season at the height of summer, during mid-July. Breeding will continue for a month until mid-August.

However, roe deer exhibit an odd trait, as the mother’s fertilized egg will not start developing until the end of December or early January. This way, they avoid giving birth during the winter months. Overall, it is unclear why mating takes place so many months before.

By May and June, roe deer start giving birth to their young.

Fallow Deer

Fallow Deer are widespread throughout Asia minor, Europe, and the United States. Their mating season occurs from September to November.

October is their most active breeding month. Males will mark off territory and fend off any other buck that enters the area. Fawns are born during late May, through June. Fallow deer doe will usually give birth to a single fawn.


The correct tools

We know a reasonable amount about the internal reproductive anatomy of box sexes of hedgehogs, both being broadly similar to the construction found in most placental mammals. The reproductive structures of the male have, however, been less well studied. Thanks to the Sir Richard Owen&rsquos nineteenth century opus on vertebrate anatomy, we know that the penis of the hedgehog is what biologists refer to as of &ldquobulbospongiosus&ndashtype&rdquo. In other words, it has a muscle (the bulbospongiosus) covering the tip that helps sustain an erection as well as help ejaculation. In volume three of his work, published in 1868, Owen described how:

&ldquoThe penis is long and bent when at rest. There are two 'levatores' which rise from the ischial tuberosities behind the 'erectores'.&rdquo

So, as Reeve confirms in Hedgehogs, erection is achieved by engorgement of spongey tissue known as the corpus cavernosum and the muscles running down the length of the penis. This is interesting, because many mammals, and particularly the &ldquoinsectivores&rdquo, have evolved a penis bone called a baculum (sometimes, the &ldquoos penis&rdquo). This is a special skeletal element that maintains the erection, rather than relying on muscles and hydraulics. Several Internet sites, including WikiPedia, state that hedgehogs possess a baculum but, as far as I can ascertain, this doesn&rsquot appear to be the case.

In 2016, a team of researchers led by Ghasem Akbari at the University of Tabriz investigated the anatomy of seven adult male hedgehogs from the Azerbaijan in Iran. The results of their study, published in Folia Morphologica, show no evidence of a baculum in any of their subjects. Instead, their analysis confirms that the erection appears to be maintained by blood pressure and muscles. Of particular note was the presence of two small downward-pointing nail-like structures made of keratin at the tip of the penis, which the anatomists suggest may play a role in helping anchor the penis during penetration.

Figures for penis length are more difficult to come by in the literature. In Hedgehogs, Nigel Reeve mentioned that he&rsquod not found any exact measurements, while in their Natural Hedgehog, Lenni Sykes and Jane Durrant wrote that the penis extends from the middle of the abdomen to beyond the nose, which suggests the erect penis is several centimetres long. During their study of Iranian hogs, Akbari and his colleagues found that the average penis length was 7.2cm (2.8 in.). This measurement aligns more or less with the video footage from our garden and a trailcam video captured by Paula Felischmann in 2014 that shows a hedgehog in a nest box cleaning its penis &ndash the full penis is obscured by the bedding material, but it appears to be several centimetres in length.

In her detailed review of hedgehog reproductive anatomy, published in 1934, King&rsquos College zoologist Marjorie Allanson noted that the weight of the penis didn&rsquot appear to vary according to season, but it was heavier in larger and older animals, ranging from 2.5g to just over 6g (0.09-0.2 oz.). Unlike the penis, the accessory glands do vary seasonally and, during the peak of the rut, Reeve noted that the male reproductive tract may account for 10% of the animal&rsquos body weight and the seminal vesicles alone can have increased ten-fold (to 30g/1 oz.) from their regressed hibernation state.

In the female, the vagina is in a regressed state during hibernation, enlarging at the beginning of the breeding season and becoming dilated during oestrus, although subsiding a little during pseudo-pregnancy (see: Breeding Biology - Oestrous & Gestation). Located at the rear of the female and close to the border of the spines, the vaginal opening is surrounded by coarse fur and not spines.


Résumé

Chez de nombreux oiseaux, les mâles reproducteurs présentent des couleurs vives, produisent des chants, et s’engagent dans une défense active du territoire, alors que les femelles sont moins voyantes. Par conséquent, il est parfois considéré qu’au cours de la saison de reproduction, les mâles sont plus affectés par la prédation que les femelles. Néanmoins, plusieurs études ont rapporté un taux de prédation plus élevé chez les femelles, ce qui suggère que des traits autres que la coloration et le comportement d’acquisition d’un partenaire jouent un rôle important dans la détermination du taux de prédation pour chacun des sexes. Les travaux théoriques et empiriques suggèrent que le comportement et le taux de quête alimentaire sont des éléments clés en ce qui concerne le risque de prédation. Nous examinons cette possibilité dans une étude sur la reproduction de Turdus merula et sur leur prédation par Accipiter nisus. Les femelles Turdus merula consacrent plus de temps à la quête alimentaire que les mâles et se tiennent à proximité du sol, que ce soit tôt ou tard dans la saison de reproduction. En se basant sur cette observation, nous avons prédit que les femelles devraient être moins affectées par la prédation que les mâles. Parmi les 98 Turdus merula collectés dans 33 territoires de Accipiter nisus au cours de 4 années, 56 étaient des femelles et 44 des mâles. En se basant sur ce sex-ratio biaisé dans le sens des mâles, les femelles Turdus merula étaient plus affectés par la prédation que les mâles. Pour les oiseaux reproducteurs, ces résultats indiquent un compromis entre les efforts de quête alimentaire et la taux de prédation, ce qui joue un rôle important dans le dichromatisme sexuel (sélection pour le camouflage de la femelle), le sex-ratio de la population, et les comportements des deux sexes.

The trade-off between foraging and anti-predator vigilance has received much attention (e.g. Lima and Dill 1990, Dukas and Kamil 2000). A general assumption is that increased foraging leads to reduced antipredator vigilance, thereby raising the predation risk. Indirect support for this prediction are behavioral (e.g. foraging close to cover, reduced foraging) and physiological (e.g. mass loss) responses to increased perceived risk of predation ( Suhonen 1993, Lilliendahl 1997). In addition, individual vigilance decreases when prey group size increases ( Roberts 1996). In Blue Tits (Parus caeruleus), predator detection is delayed when individuals face more complex foraging tasks ( Kaby and Lind 2003). Birds normally spend a substantial part of the day foraging, but few studies have quantified foraging behavior and its relation to predation mortality.

In breeding birds, males often display elaborate colors, produce song, and engage in territory defense, which may be conspicuous to predators ( Andersson 1994, Zuk and Kolluru 1998). Females are normally less conspicuous. However, several studies report female-biased predation ( Kenward et al. 1981, Angelstam 1984, Sargeant et al. 1984, Widén 1987, Götmark et al. 1997 but see Gardarsson 1971, Sodhi and Oliphant 1993). It may be energetically costly for females to produce eggs, incubate, and rear chicks ( Tinbergen and Dietz 1994, Ward 1996). To meet energy demands, females need to for-age intensively, which may make them less vigilant ( Lima and Dill 1990, Dukas and Kamil 2000). Foraging may also make females easier for predators to detect, because of the increased activity. Hence, foraging may be an important determinant of predation risk for breeding males and females. During egg production and incubation, females also gain (and lose) weight, which may affect their ability to escape predators ( Witter et al. 1994, Kullberg et al. 1996, Veasey et al. 2000).

In the Chaffinch (Fringilla coelebs), Götmark et al. (1997) reported higher Eurasian Sparrowhawk (Accipiter nisus hereafter “sparrowhawk”) predation on females than on males in the breeding season. Females spent more time foraging and were more active than males, behaviors that likely influenced predation risk. However, sparrowhawk predation on male and female Pied Flycatchers (Ficedula hypoleuca) differed little ( Post and Götmark 2006). Female Pied Flycatchers foraged more and were more active than males, but were less exposed and found higher in the vegetation. A negative relationship between predation risk and cover is likely ( Tinbergen 1946, Newton 1986 see also Sodhi and Oliphant 1993, Suhonen 1993, Götmark and Post 1996). Furthermore, predation risk in forests may decrease with increased perch or foraging height ( Selås 1993, Götmark and Post 1996 see also Gray 1987). Pied Flycatcher females spend most of their time perched in trees, making short foraging bouts, which allows them to spend more time in cover ( Post and Götmark 2006). By contrast, Chaffinch females spend more time on the ground, actively foraging, which may reduce vigilance, increase the risk of being detected by predators, and bias predation toward females.

Here, we investigate the assumption that predation risk increases with foraging effort in breeding Eurasian Blackbirds (Turdus merula hereafter “blackbirds”), which mainly forage on the ground in woodland and semi-open habitats and are common prey of sparrowhawks. For two years, we observed the behavior of male and female blackbirds during two breeding stages. Behaviors such as time spent foraging, foraging rate, exposure, and perch height were analyzed. The results suggested that females should suffer higher predation risk. To directly test the prediction that predation mortality is higher for females than for males, we analyzed the number of blackbirds killed by sparrowhawks.


Results

Body and Testicular Morphometry

General body morphometrics did not differ (P > 0.05) across reproductive seasons. Data from example traits including body mass, chest girth, and abdominal girth are presented in Table 1. In contrast, there were changes (P < 0.05) in testis size among the designated reproductive seasons. Total testicular volume increased nearly twofold (P < 0.05) from the nonbreeding to prebreeding season. A further increase (P < 0.05) was observed by the peak breeding period that was sustained through the late breeding interval ( Table 1). There were no differences (P > 0.05) between the size of the right and left testis with the exception of a larger (P < 0.05) left gonad during peak breeding season. Changes in testis size over time reflected both increased gonadal length and increased gonadal width ( Table 1).

Seasonal body and testicular morphometry in giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 7 8 6 8 6
No. of evaluations 10 19 9 19 8
Body morphometry *
Body weight (kg) 114.3 ± 4.1 119.1 ± 3.2 127.9 ± 4.1 117.1 ± 3.8 107.5 ± 5.1
Chest girth (cm) 108.1 ± 4.2 109.0 ± 1.7 114.3 ± 2.2 108.4 ± 2.2 120.4 ± 9.0
Abdominal girth (cm) 113.3 ± 3.8 112.1 ± 2.3 119.3 ± 3.5 118.2 ± 6.8 112.5 ± 3.3
Testicular morphometry *
Total testicular volume (cm 3 ) 246.9 ± 24.2 a 325.8 ± 22.7 a , b 369.6 ± 31.4 b 279.0 ± 15.7 a , b 125.3 ± 8.8 c
Right testis volume (cm 3 ) 129.3 ± 13.2 a 169.6 ± 13.9 a 175.1 ± 12.5 a 136.1 ± 8.3 a 60.4 ± 4.6 b
Right testis length (cm) 7.4 ± 0.4 a , b 8.3 ± 0.2 a 8.7 ± 0.4 a 8.2 ± 0.2 a 6.4 ± 0.3 b
Right testis width (cm) 5.7 ± 0.2 a 6.1 ± 0.2 a 6.2 ± 0.2 a 5.6 ± 0.1 a 4.2 ± 0.1 b
Left testis volume (cm 3 ) 117.6 ± 11.7 a 156.2 ± 10.4 a , b 194.4 ± 20.6 b 142.9 ± 9.5 a , b 64.9 ± 4.6 c
Left testis length (cm) 7.5 ± 0.3 a 8.3 ± 0.2 a , b 9.0 ± 0.6 b 8.1 ± 0.2 a , b 6.2 ± 0.2 c
Left testis width (cm) 5.4 ± 0.2 a 5.9 ± 0.1 a , b 6.3 ± 0.2 b 5.8 ± 0.2 a , b 4.4 ± 0.1 c
. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 7 8 6 8 6
No. of evaluations 10 19 9 19 8
Body morphometry *
Body weight (kg) 114.3 ± 4.1 119.1 ± 3.2 127.9 ± 4.1 117.1 ± 3.8 107.5 ± 5.1
Chest girth (cm) 108.1 ± 4.2 109.0 ± 1.7 114.3 ± 2.2 108.4 ± 2.2 120.4 ± 9.0
Abdominal girth (cm) 113.3 ± 3.8 112.1 ± 2.3 119.3 ± 3.5 118.2 ± 6.8 112.5 ± 3.3
Testicular morphometry *
Total testicular volume (cm 3 ) 246.9 ± 24.2 a 325.8 ± 22.7 a , b 369.6 ± 31.4 b 279.0 ± 15.7 a , b 125.3 ± 8.8 c
Right testis volume (cm 3 ) 129.3 ± 13.2 a 169.6 ± 13.9 a 175.1 ± 12.5 a 136.1 ± 8.3 a 60.4 ± 4.6 b
Right testis length (cm) 7.4 ± 0.4 a , b 8.3 ± 0.2 a 8.7 ± 0.4 a 8.2 ± 0.2 a 6.4 ± 0.3 b
Right testis width (cm) 5.7 ± 0.2 a 6.1 ± 0.2 a 6.2 ± 0.2 a 5.6 ± 0.1 a 4.2 ± 0.1 b
Left testis volume (cm 3 ) 117.6 ± 11.7 a 156.2 ± 10.4 a , b 194.4 ± 20.6 b 142.9 ± 9.5 a , b 64.9 ± 4.6 c
Left testis length (cm) 7.5 ± 0.3 a 8.3 ± 0.2 a , b 9.0 ± 0.6 b 8.1 ± 0.2 a , b 6.2 ± 0.2 c
Left testis width (cm) 5.4 ± 0.2 a 5.9 ± 0.1 a , b 6.3 ± 0.2 b 5.8 ± 0.2 a , b 4.4 ± 0.1 c

Within a row, values with different superscripts denote differences among seasons (P < 0.05).

Seasonal body and testicular morphometry in giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 7 8 6 8 6
No. of evaluations 10 19 9 19 8
Body morphometry *
Body weight (kg) 114.3 ± 4.1 119.1 ± 3.2 127.9 ± 4.1 117.1 ± 3.8 107.5 ± 5.1
Chest girth (cm) 108.1 ± 4.2 109.0 ± 1.7 114.3 ± 2.2 108.4 ± 2.2 120.4 ± 9.0
Abdominal girth (cm) 113.3 ± 3.8 112.1 ± 2.3 119.3 ± 3.5 118.2 ± 6.8 112.5 ± 3.3
Testicular morphometry *
Total testicular volume (cm 3 ) 246.9 ± 24.2 a 325.8 ± 22.7 a , b 369.6 ± 31.4 b 279.0 ± 15.7 a , b 125.3 ± 8.8 c
Right testis volume (cm 3 ) 129.3 ± 13.2 a 169.6 ± 13.9 a 175.1 ± 12.5 a 136.1 ± 8.3 a 60.4 ± 4.6 b
Right testis length (cm) 7.4 ± 0.4 a , b 8.3 ± 0.2 a 8.7 ± 0.4 a 8.2 ± 0.2 a 6.4 ± 0.3 b
Right testis width (cm) 5.7 ± 0.2 a 6.1 ± 0.2 a 6.2 ± 0.2 a 5.6 ± 0.1 a 4.2 ± 0.1 b
Left testis volume (cm 3 ) 117.6 ± 11.7 a 156.2 ± 10.4 a , b 194.4 ± 20.6 b 142.9 ± 9.5 a , b 64.9 ± 4.6 c
Left testis length (cm) 7.5 ± 0.3 a 8.3 ± 0.2 a , b 9.0 ± 0.6 b 8.1 ± 0.2 a , b 6.2 ± 0.2 c
Left testis width (cm) 5.4 ± 0.2 a 5.9 ± 0.1 a , b 6.3 ± 0.2 b 5.8 ± 0.2 a , b 4.4 ± 0.1 c
. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 7 8 6 8 6
No. of evaluations 10 19 9 19 8
Body morphometry *
Body weight (kg) 114.3 ± 4.1 119.1 ± 3.2 127.9 ± 4.1 117.1 ± 3.8 107.5 ± 5.1
Chest girth (cm) 108.1 ± 4.2 109.0 ± 1.7 114.3 ± 2.2 108.4 ± 2.2 120.4 ± 9.0
Abdominal girth (cm) 113.3 ± 3.8 112.1 ± 2.3 119.3 ± 3.5 118.2 ± 6.8 112.5 ± 3.3
Testicular morphometry *
Total testicular volume (cm 3 ) 246.9 ± 24.2 a 325.8 ± 22.7 a , b 369.6 ± 31.4 b 279.0 ± 15.7 a , b 125.3 ± 8.8 c
Right testis volume (cm 3 ) 129.3 ± 13.2 a 169.6 ± 13.9 a 175.1 ± 12.5 a 136.1 ± 8.3 a 60.4 ± 4.6 b
Right testis length (cm) 7.4 ± 0.4 a , b 8.3 ± 0.2 a 8.7 ± 0.4 a 8.2 ± 0.2 a 6.4 ± 0.3 b
Right testis width (cm) 5.7 ± 0.2 a 6.1 ± 0.2 a 6.2 ± 0.2 a 5.6 ± 0.1 a 4.2 ± 0.1 b
Left testis volume (cm 3 ) 117.6 ± 11.7 a 156.2 ± 10.4 a , b 194.4 ± 20.6 b 142.9 ± 9.5 a , b 64.9 ± 4.6 c
Left testis length (cm) 7.5 ± 0.3 a 8.3 ± 0.2 a , b 9.0 ± 0.6 b 8.1 ± 0.2 a , b 6.2 ± 0.2 c
Left testis width (cm) 5.4 ± 0.2 a 5.9 ± 0.1 a , b 6.3 ± 0.2 b 5.8 ± 0.2 a , b 4.4 ± 0.1 c

Within a row, values with different superscripts denote differences among seasons (P < 0.05).

Androgen Concentrations and Patterns

Mean fecal androgen concentrations in male giant pandas differed (P < 0.05) over time, with basal levels (74.2 ± 3.9 ng/g dry feces n = 414 samples) measured during the late breeding season ( Fig. 2). Values peaked (P < 0.05) during the prebreeding (160.6 ± 4.4 ng/g dry feces n = 790 samples) and early breeding (158.0 ± 8.2 ng/g dry feces n = 335) periods. Once the interval of peak female sexual activity was reached, the amount of excreted androgen in the male giant panda was in decline (108.6 ± 7.9 ng/g dry feces n = 196 samples), a trend that continued to the late period mean nadir (74.3 ± 3.9 ng/g dry feces n = 427 samples) ( Fig. 2).

Total androgen concentrations in adult male giant pandas (n = 8) in China over a 3-yr period. Bars represent mean (±SEM) total androgens within a season during the prebreeding (October 1–January 31), early breeding (February 1–March 21), peak breeding (March 22–April 15), late breeding (April 16–May 31), and nonbreeding (June 1–September 30) seasons. Means with different superscripts represent differences among periods (P < 0.05).

Total androgen concentrations in adult male giant pandas (n = 8) in China over a 3-yr period. Bars represent mean (±SEM) total androgens within a season during the prebreeding (October 1–January 31), early breeding (February 1–March 21), peak breeding (March 22–April 15), late breeding (April 16–May 31), and nonbreeding (June 1–September 30) seasons. Means with different superscripts represent differences among periods (P < 0.05).

Temporal fluctuations in fecal androgen concentrations were best reflected in weekly means for the entire male cohort ( Fig. 3). The iterative mean showing an androgenic baseline was calculated ( Fig. 3) within two standard deviations (indicated by the shaded area). In all cases, nadir androgen excretion was observed in the late breeding season (mid-April–May) with variable concentrations remaining near baseline until October ( Fig. 3). The prebreeding interval (October–January) was associated with increased androgen production that was sustained from February through mid-April (early and peak breeding periods Fig. 3), intervals when most females were in estrus ( Fig. 1). Interestingly, by April 15 (when 19% of females still had not displayed estrus), androgen production was declining and reached nadir about 6 wk before onset of the female nonbreeding season ( Fig. 3). There were subtle, but nonsignificant (P > 0.05), variations among males ( Fig. 4). Although there were clear trends in androgen fluctuations within individuals over time ( Fig. 4), these changes were not significant (P > 0.05). Additionally, onset and rate of increased and decreased androgen metabolite production was consistent (P > 0.05) within an individual from year to year (data not shown).

Fecal androgens, testicular volume, and total sperm per ejaculate in male giant pandas (n = 8) in China over a 3-yr period. Mean (±SEM) fecal androgens (solid circles) during prebreeding (October 1–January 31), early (February 1–March 21), peak (March 22–April 15), and late (April 16–May 31) breeding seasons, as well as the nonbreeding (June 1–September 30) season. Baseline (±SEM) androgen in the dashed, shaded area. Mean (±SEM) values for testicular volume are presented by gray bars and total sperm per ejaculate by black bars. Bars with different letters within each trait represent differences among seasons (P < 0.05).

Fecal androgens, testicular volume, and total sperm per ejaculate in male giant pandas (n = 8) in China over a 3-yr period. Mean (±SEM) fecal androgens (solid circles) during prebreeding (October 1–January 31), early (February 1–March 21), peak (March 22–April 15), and late (April 16–May 31) breeding seasons, as well as the nonbreeding (June 1–September 30) season. Baseline (±SEM) androgen in the dashed, shaded area. Mean (±SEM) values for testicular volume are presented by gray bars and total sperm per ejaculate by black bars. Bars with different letters within each trait represent differences among seasons (P < 0.05).

Representative weekly (±SEM) androgen profiles for two male giant pandas during the prebreeding (October 1–January 31), early (February 1–March 21), peak (March 22–April 15), and late (April 16–May 31) breeding seasons, as well as the nonbreeding (June 1–September 30) season, over 3 consecutive yr. Baseline androgen (dashed line) was determined by hormone iterations using all fecal androgen samples for each male. Two standard deviations above and below baseline androgen are represented by the shaded area.

Representative weekly (±SEM) androgen profiles for two male giant pandas during the prebreeding (October 1–January 31), early (February 1–March 21), peak (March 22–April 15), and late (April 16–May 31) breeding seasons, as well as the nonbreeding (June 1–September 30) season, over 3 consecutive yr. Baseline androgen (dashed line) was determined by hormone iterations using all fecal androgen samples for each male. Two standard deviations above and below baseline androgen are represented by the shaded area.

Ejaculate Characteristics

None of the six males produced seminal fluid (or spermic ejaculate) during the nonbreeding season, and only three of six individuals did so during the prebreeding season ( Table 2). In contrast, all males produced spermic ejaculate during the early, peak, and late breeding seasons. The sperm concentration of ejaculates varied throughout the year and was consistent with increases in total testes volume ( Table 1) and mean weekly androgen excretion ( Fig. 3). Ejaculate volume, sperm concentration, and total sperm per ejaculate were lower (P < 0.05) in the prebreeding compared to the early, peak, and late breeding periods ( Table 2). Time of year had no influence (P > 0.05) on ejaculate pH or sperm motility traits ( Table 2).

Seasonal ejaculate and sperm traits in giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 3) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 6 8 5 8 6
No. of semen collections 11 17 7 20 8
No. of spermic ejaculates 4 16 6 19 0
Ejaculate volume (ml) * 0.2 ± 0.1 a 2.3 ± 0.4 b 2.9 ± 0.8 b 1.3 ± 0.2 b 0.0 c
Ejaculate pH * 7.8 ± 0.9 8.6 ± 0.1 8.5 ± 0.1 8.6 ± 0.1 n/a
Sperm concentration/ml (× 10 6 ) * 601.3 ± 586.4 a 1955.3 ± 371.8 b 1669.7 ± 508.8 b 1780.4 ± 241.0 b 0.0 c
Total sperm/ejaculate (× 10 6 ) * 61.9 ± 58.5 a 3571.2 ± 744.6 b 2178.2 ± 299.5 b 2414.9 ± 519.8 b 0.0 c
Sperm motility (%) * 58.8 ± 7.2 78.5 ± 2.2 85.4 ± 2.7 77.0 ± 4.7 n/a
Sperm forward progression * † 2.6 ± 0.6 3.8 ± 0.2 4.3 ± 0.2 4.0 ± 0.2 n/a
Sperm morphology (%) *
Normal sperm 42.3 ± 13.8 60.0 ± 5.1 74.4 ± 3.6 58.7 ± 4.1 n/a
Abnormal sperm 57.7 ± 13.8 40.0 ± 5.1 25.5 ± 3.6 41.3 ± 4.2 n/a
Head defects 5.0 ± 4.3 1.8 ± 0.5 3.2 ± 2.4 1.2 ± 0.3 n/a
Midpiece defects 13.3 ± 7.0 25.2 ± 4.2 15.2 ± 3.5 21.4 ± 3.4 n/a
Flagellar defects 39.4 ± 11.7 a 13.0 ± 2.6 b 7.1 ± 1.7 b 18.7 ± 2.6 b n/a
Acrosomal integrity (%) *
Normal apical ridge 80.7 ± 7.4 a , b 87.9 ± 1.6 a 89.4 ± 3.3 a 71.1 ± 3.4 b n/a
Damaged apical ridge 18.0 ± 6.1 a , b 10.8 ± 1.1 a 9.2 ± 2.3 a 24.4 ± 3.3 b n/a
Missing apical ridge 1.3 ± 1.3 1.1 ± 0.3 2.6 ± 1.3 5.2 ± 1.5 n/a
Loose acrosomal cap 0.0 ± 0.0 0.2 ± 0.1 0.0 ± 0.0 0.0 ± 0.0 n/a
. Prebreeding (Oct 1–Jan 3) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 6 8 5 8 6
No. of semen collections 11 17 7 20 8
No. of spermic ejaculates 4 16 6 19 0
Ejaculate volume (ml) * 0.2 ± 0.1 a 2.3 ± 0.4 b 2.9 ± 0.8 b 1.3 ± 0.2 b 0.0 c
Ejaculate pH * 7.8 ± 0.9 8.6 ± 0.1 8.5 ± 0.1 8.6 ± 0.1 n/a
Sperm concentration/ml (× 10 6 ) * 601.3 ± 586.4 a 1955.3 ± 371.8 b 1669.7 ± 508.8 b 1780.4 ± 241.0 b 0.0 c
Total sperm/ejaculate (× 10 6 ) * 61.9 ± 58.5 a 3571.2 ± 744.6 b 2178.2 ± 299.5 b 2414.9 ± 519.8 b 0.0 c
Sperm motility (%) * 58.8 ± 7.2 78.5 ± 2.2 85.4 ± 2.7 77.0 ± 4.7 n/a
Sperm forward progression * † 2.6 ± 0.6 3.8 ± 0.2 4.3 ± 0.2 4.0 ± 0.2 n/a
Sperm morphology (%) *
Normal sperm 42.3 ± 13.8 60.0 ± 5.1 74.4 ± 3.6 58.7 ± 4.1 n/a
Abnormal sperm 57.7 ± 13.8 40.0 ± 5.1 25.5 ± 3.6 41.3 ± 4.2 n/a
Head defects 5.0 ± 4.3 1.8 ± 0.5 3.2 ± 2.4 1.2 ± 0.3 n/a
Midpiece defects 13.3 ± 7.0 25.2 ± 4.2 15.2 ± 3.5 21.4 ± 3.4 n/a
Flagellar defects 39.4 ± 11.7 a 13.0 ± 2.6 b 7.1 ± 1.7 b 18.7 ± 2.6 b n/a
Acrosomal integrity (%) *
Normal apical ridge 80.7 ± 7.4 a , b 87.9 ± 1.6 a 89.4 ± 3.3 a 71.1 ± 3.4 b n/a
Damaged apical ridge 18.0 ± 6.1 a , b 10.8 ± 1.1 a 9.2 ± 2.3 a 24.4 ± 3.3 b n/a
Missing apical ridge 1.3 ± 1.3 1.1 ± 0.3 2.6 ± 1.3 5.2 ± 1.5 n/a
Loose acrosomal cap 0.0 ± 0.0 0.2 ± 0.1 0.0 ± 0.0 0.0 ± 0.0 n/a

Values are means ± SEM. No available ejaculate is represented as n/a.

Within a row, values with different superscripts denote differences among seasons (P < 0.05).

Seasonal ejaculate and sperm traits in giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 3) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 6 8 5 8 6
No. of semen collections 11 17 7 20 8
No. of spermic ejaculates 4 16 6 19 0
Ejaculate volume (ml) * 0.2 ± 0.1 a 2.3 ± 0.4 b 2.9 ± 0.8 b 1.3 ± 0.2 b 0.0 c
Ejaculate pH * 7.8 ± 0.9 8.6 ± 0.1 8.5 ± 0.1 8.6 ± 0.1 n/a
Sperm concentration/ml (× 10 6 ) * 601.3 ± 586.4 a 1955.3 ± 371.8 b 1669.7 ± 508.8 b 1780.4 ± 241.0 b 0.0 c
Total sperm/ejaculate (× 10 6 ) * 61.9 ± 58.5 a 3571.2 ± 744.6 b 2178.2 ± 299.5 b 2414.9 ± 519.8 b 0.0 c
Sperm motility (%) * 58.8 ± 7.2 78.5 ± 2.2 85.4 ± 2.7 77.0 ± 4.7 n/a
Sperm forward progression * † 2.6 ± 0.6 3.8 ± 0.2 4.3 ± 0.2 4.0 ± 0.2 n/a
Sperm morphology (%) *
Normal sperm 42.3 ± 13.8 60.0 ± 5.1 74.4 ± 3.6 58.7 ± 4.1 n/a
Abnormal sperm 57.7 ± 13.8 40.0 ± 5.1 25.5 ± 3.6 41.3 ± 4.2 n/a
Head defects 5.0 ± 4.3 1.8 ± 0.5 3.2 ± 2.4 1.2 ± 0.3 n/a
Midpiece defects 13.3 ± 7.0 25.2 ± 4.2 15.2 ± 3.5 21.4 ± 3.4 n/a
Flagellar defects 39.4 ± 11.7 a 13.0 ± 2.6 b 7.1 ± 1.7 b 18.7 ± 2.6 b n/a
Acrosomal integrity (%) *
Normal apical ridge 80.7 ± 7.4 a , b 87.9 ± 1.6 a 89.4 ± 3.3 a 71.1 ± 3.4 b n/a
Damaged apical ridge 18.0 ± 6.1 a , b 10.8 ± 1.1 a 9.2 ± 2.3 a 24.4 ± 3.3 b n/a
Missing apical ridge 1.3 ± 1.3 1.1 ± 0.3 2.6 ± 1.3 5.2 ± 1.5 n/a
Loose acrosomal cap 0.0 ± 0.0 0.2 ± 0.1 0.0 ± 0.0 0.0 ± 0.0 n/a
. Prebreeding (Oct 1–Jan 3) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. of males 6 8 5 8 6
No. of semen collections 11 17 7 20 8
No. of spermic ejaculates 4 16 6 19 0
Ejaculate volume (ml) * 0.2 ± 0.1 a 2.3 ± 0.4 b 2.9 ± 0.8 b 1.3 ± 0.2 b 0.0 c
Ejaculate pH * 7.8 ± 0.9 8.6 ± 0.1 8.5 ± 0.1 8.6 ± 0.1 n/a
Sperm concentration/ml (× 10 6 ) * 601.3 ± 586.4 a 1955.3 ± 371.8 b 1669.7 ± 508.8 b 1780.4 ± 241.0 b 0.0 c
Total sperm/ejaculate (× 10 6 ) * 61.9 ± 58.5 a 3571.2 ± 744.6 b 2178.2 ± 299.5 b 2414.9 ± 519.8 b 0.0 c
Sperm motility (%) * 58.8 ± 7.2 78.5 ± 2.2 85.4 ± 2.7 77.0 ± 4.7 n/a
Sperm forward progression * † 2.6 ± 0.6 3.8 ± 0.2 4.3 ± 0.2 4.0 ± 0.2 n/a
Sperm morphology (%) *
Normal sperm 42.3 ± 13.8 60.0 ± 5.1 74.4 ± 3.6 58.7 ± 4.1 n/a
Abnormal sperm 57.7 ± 13.8 40.0 ± 5.1 25.5 ± 3.6 41.3 ± 4.2 n/a
Head defects 5.0 ± 4.3 1.8 ± 0.5 3.2 ± 2.4 1.2 ± 0.3 n/a
Midpiece defects 13.3 ± 7.0 25.2 ± 4.2 15.2 ± 3.5 21.4 ± 3.4 n/a
Flagellar defects 39.4 ± 11.7 a 13.0 ± 2.6 b 7.1 ± 1.7 b 18.7 ± 2.6 b n/a
Acrosomal integrity (%) *
Normal apical ridge 80.7 ± 7.4 a , b 87.9 ± 1.6 a 89.4 ± 3.3 a 71.1 ± 3.4 b n/a
Damaged apical ridge 18.0 ± 6.1 a , b 10.8 ± 1.1 a 9.2 ± 2.3 a 24.4 ± 3.3 b n/a
Missing apical ridge 1.3 ± 1.3 1.1 ± 0.3 2.6 ± 1.3 5.2 ± 1.5 n/a
Loose acrosomal cap 0.0 ± 0.0 0.2 ± 0.1 0.0 ± 0.0 0.0 ± 0.0 n/a

Values are means ± SEM. No available ejaculate is represented as n/a.

Within a row, values with different superscripts denote differences among seasons (P < 0.05).

Most ejaculates contained more than 50% structurally normal spermatozoa, with most malformations occurring in the midpiece or flagellum ( Table 2). Head pleiomorphisms generally comprised 5% or less of total spermatozoa analyzed. Flagellar deformities were more prevalent (P < 0.05) during the prebreeding than any period of the breeding season ( Table 2). The majority of structural abnormalities observed from October through January were associated with proximal cytoplasmic droplets (35.5% ± 12.4% of all recovered spermatozoa). Ejaculates also contained high percentages of spermatozoa with normal acrosomes ( Table 2). Even during the prebreeding season, at least 80% of the sperm acrosomes had a normal apical ridge. There was a modest decrease (P < 0.05) in percentage of normal acrosomes as males transitioned from the peak to late breeding season ( Table 2). Ejaculates recovered in the late breeding season contained a higher (P < 0.05) number of sperm with a damaged apical ridge compared to those during the early and peak breeding seasons. Otherwise, there was no variation in acrosomal integrity ( Table 2).

Behaviors

The frequency of behaviors associated with scent marking, vocalization, and pacing differed (P < 0.05) with season ( Table 3) with the first acceleration in activities occurring within 30–45 days of elevated androgen patterns. There was variation among males in the intensity or frequency of these behaviors, but trends within individuals were clear. For example, there was an increased frequency (P < 0.05) of males demonstrating handstand, squat, and handstand urine markings in the prebreeding or breeding seasons compared to the nonbreeding season ( Table 3). Prevalence of these behaviors tended to decline over the three phases of the breeding season, but this was nonsignificant (P > 0.05) because of variations among males. Vocalizations and pacing increased (P < 0.05) from nadir during the nonbreeding period to maximal values during the early and peak reproductive season when most females entered estrus ( Table 3).

Seasonal frequency of behaviors in male giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. males observed 8 8 8 8 8
Total scent marking (× 10 −3 ) * 23.5 ± 2.0 a 27.6 ± 2.8 a 22.5 ± 3.1 a , b 14.0 ± 1.9 a , b 9.3 ± 1.2 b
Handstand mark (× 10 −3 ) 1.8 ± 0.3 a 1.7 ± 0.4 a 0.4 ± 0.3 a , b 0.3 ± 0.2 a , b 0.1 ± 0.1 b
Leg cock mark (× 10 −3 ) 2.4 ± 0.4 2.0 ± 0.5 1.2 ± 0.5 0.4 ± 0.2 1.8 ± 0.5
Reverse mark (× 10 −3 ) 4.2 ± 0.7 3.6 ± 0.8 5.2 ± 1.5 2.1 ± 0.6 1.1 ± 0.3
Squat mark (× 10 −3 ) 8.0 ± 1.0 a , b 11.9 ± 1.9 a 6.4 ± 1.6 a , b 5.0 ± 1.1 a , b 4.8 ± 0.8 b
Handstand urine mark (× 10 −3 ) 5.7 ± 0.6 a 7.4 ± 0.9 a 8.2 ± 1.2 a 4.5 ± 0.8 a 0.5 ± 0.7 b
Leg cock urine mark (× 10 −3 ) 1.4 ± 0.3 1.0 ± 0.3 1.1 ± 0.4 1.7 ± 0.5 1.0 ± 0.2
Affiliative interaction (× 10 −3 ) * 0.1 ± 0.0 2.8 ± 1.2 2.3 ± 1.1 0.1 ± 0.1 0.5 ± 0.3
Barrier interaction (× 10 −3 ) * 9.3 ± 1.0 25.5 ± 2.2 33.0 ± 4.6 14.8 ± 1.8 4.7 ± 0.7
Total olfactory behaviors (× 10 −3 ) * 15.5 ± 1.8 15.6 ± 2.9 41.4 ± 10.1 27.1 ± 4.8 9.4 ± 1.2
Scent anoint (× 10 −3 ) 3.6 ± 1.1 2.4 ± 0.8 4.7 ± 1.8 3.2 ± 1.4 1.4 ± 4.9
Open-mouth olfactory (× 10 −3 ) 6.1 ± 0.9 6.1 ± 1.0 21.3 ± 4.6 16.3 ± 2.7 6.0 ± 0.8
Lick olfactory (× 10 −3 ) 5.6 ± 0.7 7.1 ± 2.2 15.4 ± 6.2 7.6 ± 1.8 1.8 ± 0.5
Vocalization (× 10 −3 ) * 119.5 ± 16.3 a , b 237.3 ± 36.5 a 491.0 ± 91.8 a 171.2 ± 27.2 a , b 86.0 ± 12.2 b
Investigate/explore (× 10 −3 ) * 42.5 ± 2.2 42.5 ± 4.4 57.9 ± 7.3 50.6 ± 4.4 22.2 ± 1.3
Nonmotile stereotypy (× 10 −3 ) * 44.7 ± 10.0 23.7 ± 6.5 10.6 ± 2.4 17.9 ± 8.3 36.7 ± 10.4
Total motile stereotypy (× 10 −3 ) * 40.2 ± 3.0 49.2 ± 3.8 44.1 ± 5.2 31.2 ± 3.7 20.1 ± 2.5
Locomotor stereotypy (× 10 −3 ) 19.2 ± 6.9 16.3 ± 2.0 7.9 ± 1.8 4.8 ± 1.1 5.9 ± 1.3
Pace (× 10 −3 ) 21.0 ± 2.1 a 32.9 ± 3.3 b 36.2 ± 4.6 b 26.4 ± 3.3 b 14.2 ± 1.9 a
. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. males observed 8 8 8 8 8
Total scent marking (× 10 −3 ) * 23.5 ± 2.0 a 27.6 ± 2.8 a 22.5 ± 3.1 a , b 14.0 ± 1.9 a , b 9.3 ± 1.2 b
Handstand mark (× 10 −3 ) 1.8 ± 0.3 a 1.7 ± 0.4 a 0.4 ± 0.3 a , b 0.3 ± 0.2 a , b 0.1 ± 0.1 b
Leg cock mark (× 10 −3 ) 2.4 ± 0.4 2.0 ± 0.5 1.2 ± 0.5 0.4 ± 0.2 1.8 ± 0.5
Reverse mark (× 10 −3 ) 4.2 ± 0.7 3.6 ± 0.8 5.2 ± 1.5 2.1 ± 0.6 1.1 ± 0.3
Squat mark (× 10 −3 ) 8.0 ± 1.0 a , b 11.9 ± 1.9 a 6.4 ± 1.6 a , b 5.0 ± 1.1 a , b 4.8 ± 0.8 b
Handstand urine mark (× 10 −3 ) 5.7 ± 0.6 a 7.4 ± 0.9 a 8.2 ± 1.2 a 4.5 ± 0.8 a 0.5 ± 0.7 b
Leg cock urine mark (× 10 −3 ) 1.4 ± 0.3 1.0 ± 0.3 1.1 ± 0.4 1.7 ± 0.5 1.0 ± 0.2
Affiliative interaction (× 10 −3 ) * 0.1 ± 0.0 2.8 ± 1.2 2.3 ± 1.1 0.1 ± 0.1 0.5 ± 0.3
Barrier interaction (× 10 −3 ) * 9.3 ± 1.0 25.5 ± 2.2 33.0 ± 4.6 14.8 ± 1.8 4.7 ± 0.7
Total olfactory behaviors (× 10 −3 ) * 15.5 ± 1.8 15.6 ± 2.9 41.4 ± 10.1 27.1 ± 4.8 9.4 ± 1.2
Scent anoint (× 10 −3 ) 3.6 ± 1.1 2.4 ± 0.8 4.7 ± 1.8 3.2 ± 1.4 1.4 ± 4.9
Open-mouth olfactory (× 10 −3 ) 6.1 ± 0.9 6.1 ± 1.0 21.3 ± 4.6 16.3 ± 2.7 6.0 ± 0.8
Lick olfactory (× 10 −3 ) 5.6 ± 0.7 7.1 ± 2.2 15.4 ± 6.2 7.6 ± 1.8 1.8 ± 0.5
Vocalization (× 10 −3 ) * 119.5 ± 16.3 a , b 237.3 ± 36.5 a 491.0 ± 91.8 a 171.2 ± 27.2 a , b 86.0 ± 12.2 b
Investigate/explore (× 10 −3 ) * 42.5 ± 2.2 42.5 ± 4.4 57.9 ± 7.3 50.6 ± 4.4 22.2 ± 1.3
Nonmotile stereotypy (× 10 −3 ) * 44.7 ± 10.0 23.7 ± 6.5 10.6 ± 2.4 17.9 ± 8.3 36.7 ± 10.4
Total motile stereotypy (× 10 −3 ) * 40.2 ± 3.0 49.2 ± 3.8 44.1 ± 5.2 31.2 ± 3.7 20.1 ± 2.5
Locomotor stereotypy (× 10 −3 ) 19.2 ± 6.9 16.3 ± 2.0 7.9 ± 1.8 4.8 ± 1.1 5.9 ± 1.3
Pace (× 10 −3 ) 21.0 ± 2.1 a 32.9 ± 3.3 b 36.2 ± 4.6 b 26.4 ± 3.3 b 14.2 ± 1.9 a

Values are means ± SEM. Frequency of each behavior was recorded as the number of times behavior occurred per visible minute.

Within a row, values with different superscripts denote differences among seasons (P < 0.05).

Seasonal frequency of behaviors in male giant pandas in China during a 3-yr study.

. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. males observed 8 8 8 8 8
Total scent marking (× 10 −3 ) * 23.5 ± 2.0 a 27.6 ± 2.8 a 22.5 ± 3.1 a , b 14.0 ± 1.9 a , b 9.3 ± 1.2 b
Handstand mark (× 10 −3 ) 1.8 ± 0.3 a 1.7 ± 0.4 a 0.4 ± 0.3 a , b 0.3 ± 0.2 a , b 0.1 ± 0.1 b
Leg cock mark (× 10 −3 ) 2.4 ± 0.4 2.0 ± 0.5 1.2 ± 0.5 0.4 ± 0.2 1.8 ± 0.5
Reverse mark (× 10 −3 ) 4.2 ± 0.7 3.6 ± 0.8 5.2 ± 1.5 2.1 ± 0.6 1.1 ± 0.3
Squat mark (× 10 −3 ) 8.0 ± 1.0 a , b 11.9 ± 1.9 a 6.4 ± 1.6 a , b 5.0 ± 1.1 a , b 4.8 ± 0.8 b
Handstand urine mark (× 10 −3 ) 5.7 ± 0.6 a 7.4 ± 0.9 a 8.2 ± 1.2 a 4.5 ± 0.8 a 0.5 ± 0.7 b
Leg cock urine mark (× 10 −3 ) 1.4 ± 0.3 1.0 ± 0.3 1.1 ± 0.4 1.7 ± 0.5 1.0 ± 0.2
Affiliative interaction (× 10 −3 ) * 0.1 ± 0.0 2.8 ± 1.2 2.3 ± 1.1 0.1 ± 0.1 0.5 ± 0.3
Barrier interaction (× 10 −3 ) * 9.3 ± 1.0 25.5 ± 2.2 33.0 ± 4.6 14.8 ± 1.8 4.7 ± 0.7
Total olfactory behaviors (× 10 −3 ) * 15.5 ± 1.8 15.6 ± 2.9 41.4 ± 10.1 27.1 ± 4.8 9.4 ± 1.2
Scent anoint (× 10 −3 ) 3.6 ± 1.1 2.4 ± 0.8 4.7 ± 1.8 3.2 ± 1.4 1.4 ± 4.9
Open-mouth olfactory (× 10 −3 ) 6.1 ± 0.9 6.1 ± 1.0 21.3 ± 4.6 16.3 ± 2.7 6.0 ± 0.8
Lick olfactory (× 10 −3 ) 5.6 ± 0.7 7.1 ± 2.2 15.4 ± 6.2 7.6 ± 1.8 1.8 ± 0.5
Vocalization (× 10 −3 ) * 119.5 ± 16.3 a , b 237.3 ± 36.5 a 491.0 ± 91.8 a 171.2 ± 27.2 a , b 86.0 ± 12.2 b
Investigate/explore (× 10 −3 ) * 42.5 ± 2.2 42.5 ± 4.4 57.9 ± 7.3 50.6 ± 4.4 22.2 ± 1.3
Nonmotile stereotypy (× 10 −3 ) * 44.7 ± 10.0 23.7 ± 6.5 10.6 ± 2.4 17.9 ± 8.3 36.7 ± 10.4
Total motile stereotypy (× 10 −3 ) * 40.2 ± 3.0 49.2 ± 3.8 44.1 ± 5.2 31.2 ± 3.7 20.1 ± 2.5
Locomotor stereotypy (× 10 −3 ) 19.2 ± 6.9 16.3 ± 2.0 7.9 ± 1.8 4.8 ± 1.1 5.9 ± 1.3
Pace (× 10 −3 ) 21.0 ± 2.1 a 32.9 ± 3.3 b 36.2 ± 4.6 b 26.4 ± 3.3 b 14.2 ± 1.9 a
. Prebreeding (Oct 1–Jan 31) . Early breeding (Feb 1–Mar 21) . Peak breeding (Mar 22–Apr 15) . Late breeding (Apr 16–May 31) . Nonbreeding (Jun 1–Sep 30) .
No. males observed 8 8 8 8 8
Total scent marking (× 10 −3 ) * 23.5 ± 2.0 a 27.6 ± 2.8 a 22.5 ± 3.1 a , b 14.0 ± 1.9 a , b 9.3 ± 1.2 b
Handstand mark (× 10 −3 ) 1.8 ± 0.3 a 1.7 ± 0.4 a 0.4 ± 0.3 a , b 0.3 ± 0.2 a , b 0.1 ± 0.1 b
Leg cock mark (× 10 −3 ) 2.4 ± 0.4 2.0 ± 0.5 1.2 ± 0.5 0.4 ± 0.2 1.8 ± 0.5
Reverse mark (× 10 −3 ) 4.2 ± 0.7 3.6 ± 0.8 5.2 ± 1.5 2.1 ± 0.6 1.1 ± 0.3
Squat mark (× 10 −3 ) 8.0 ± 1.0 a , b 11.9 ± 1.9 a 6.4 ± 1.6 a , b 5.0 ± 1.1 a , b 4.8 ± 0.8 b
Handstand urine mark (× 10 −3 ) 5.7 ± 0.6 a 7.4 ± 0.9 a 8.2 ± 1.2 a 4.5 ± 0.8 a 0.5 ± 0.7 b
Leg cock urine mark (× 10 −3 ) 1.4 ± 0.3 1.0 ± 0.3 1.1 ± 0.4 1.7 ± 0.5 1.0 ± 0.2
Affiliative interaction (× 10 −3 ) * 0.1 ± 0.0 2.8 ± 1.2 2.3 ± 1.1 0.1 ± 0.1 0.5 ± 0.3
Barrier interaction (× 10 −3 ) * 9.3 ± 1.0 25.5 ± 2.2 33.0 ± 4.6 14.8 ± 1.8 4.7 ± 0.7
Total olfactory behaviors (× 10 −3 ) * 15.5 ± 1.8 15.6 ± 2.9 41.4 ± 10.1 27.1 ± 4.8 9.4 ± 1.2
Scent anoint (× 10 −3 ) 3.6 ± 1.1 2.4 ± 0.8 4.7 ± 1.8 3.2 ± 1.4 1.4 ± 4.9
Open-mouth olfactory (× 10 −3 ) 6.1 ± 0.9 6.1 ± 1.0 21.3 ± 4.6 16.3 ± 2.7 6.0 ± 0.8
Lick olfactory (× 10 −3 ) 5.6 ± 0.7 7.1 ± 2.2 15.4 ± 6.2 7.6 ± 1.8 1.8 ± 0.5
Vocalization (× 10 −3 ) * 119.5 ± 16.3 a , b 237.3 ± 36.5 a 491.0 ± 91.8 a 171.2 ± 27.2 a , b 86.0 ± 12.2 b
Investigate/explore (× 10 −3 ) * 42.5 ± 2.2 42.5 ± 4.4 57.9 ± 7.3 50.6 ± 4.4 22.2 ± 1.3
Nonmotile stereotypy (× 10 −3 ) * 44.7 ± 10.0 23.7 ± 6.5 10.6 ± 2.4 17.9 ± 8.3 36.7 ± 10.4
Total motile stereotypy (× 10 −3 ) * 40.2 ± 3.0 49.2 ± 3.8 44.1 ± 5.2 31.2 ± 3.7 20.1 ± 2.5
Locomotor stereotypy (× 10 −3 ) 19.2 ± 6.9 16.3 ± 2.0 7.9 ± 1.8 4.8 ± 1.1 5.9 ± 1.3
Pace (× 10 −3 ) 21.0 ± 2.1 a 32.9 ± 3.3 b 36.2 ± 4.6 b 26.4 ± 3.3 b 14.2 ± 1.9 a

Values are means ± SEM. Frequency of each behavior was recorded as the number of times behavior occurred per visible minute.

Within a row, values with different superscripts denote differences among seasons (P < 0.05).


Biology Teaching Resources. The Desert Locust


Mating. The male locust mounts the back of the female, applies the tip of his abdomen to hers and passes sperms into her reproductive tract. The sperms are stored in a sperm sac in the female's abdomen, and as the eggs pass down the oviduct during laying, the sperms are released and so fertilize the eggs.

Eggs. After mating, the female lays her eggs in warm, moist sand following a rainy spell. She pushes her abdomen down into the sand, extending the membranes between the segments, and burrowing to a depth of 50 or 60 mm. In this burrow, 50 to 100 eggs are laid and mixed with a frothy fluid, which hardens slightly and may help to maintain an air supply round the eggs. In 10 to 20 days depending on temperature and moisture, the eggs hatch and the nymphs make their way to the surface and emerge as &lsquohoppers&rsquo (like miniature adults but wingless at this stage).

Swarming. If food is in adequate supply and the hoppers are not forced to crowd together when they emerge from the eggs, the locusts live their lives separately as do other grasshoppers. If, however, the hoppers are crowded together for one reason or another, they enter a gregarious phase of activity. The hoppers tend to keep together in a band and move forward together. The crowding effect also results in a change of colour from the normal green, buff or brown to a striking black and yellow (or orange) coloration. There are also structural differences from the solitary form. The bands of hoppers vary in size from hundreds to millions, covering a few square metres or several square kilometres, depending partly on the age of the hoppers and how many bands have combined. As hoppers, they migrate only a few kilometres each day, basking in the early morning sun until their body temperature rises to a level which allows them to move off and eat all the vegetation in their path. When the temperature drops at night they climb bushes and plant stems and remain immobile.

After the final ecdysis, the adult locusts take to the wing and after a few days of short flights set off on extensive migrations, settling at night and in the middle of the day when it is hottest. A medium-sized swarm may contain a thousand million locusts and cover an area of 20 square kilometres. Such a swarm will consume some 3000 tonnes of vegetation per day and so if a swarm lands on agricultural crops, the locusts will strip them of every vestige of leaf and edible stem.

The swarms may travel many hundreds of kilometres from their place of origin, e.g. from Africa to India, and the females will lay eggs during their journey, so leaving the nucleus of successive swarms within a few weeks.

Methods of control. The range of the adult locusts is so great that international cooperation is essential for effective control. A swarm may originate in India but cause devastating damage to crops in Africa. Sixty countries in Asia and Africa are threatened by swarms of the desert locust.

The main method of control is by spreading poisoned bait, for example bran containing insecticide, in the path of the migrating bands of hoppers. The insecticide kills them by being eaten and by its contact with their bodies. Poisoned bait can be used only when the locality of the hoppers is known, and a careful watch must be kept over wide areas so that swarms are discovered as soon as possible after they emerge. The information is then sent to anti-locust centres, e.g. in Nairobi or London, and trucks and personnel are mobilized to take the bait to the appropriate location.

Other methods employed are to spray insecticides over swarms of hoppers or settled adults using aircraft or motor vehicles, or to spray the vegetation in the path of the hoppers. If the region of egg-laying is known, the vegetation in the area can be sprayed with an insecticide which kills the hoppers at their first meal. The danger with all spraying techniques is that the chemicals used may be poisonous to humans and other animals, particularly if used on food crops.

Two other species, the red locust and the migratory locust, have been held in check for many years by effective control measures, but the desert locust still constitutes a major threat. Constant vigilance and international cooperation are needed if crops are to be protected against this insect.

Currently it is being discussed whether the hazardous nature of the insecticides and the expense of spreading them is a cost effective way of controlling the desert locust. However, new and safer insecticides are being produced all the time and there is little doubt that farmers whose crops are threatened by locust plagues will want control measures to continue.

For illustrations to accompany this article see Insect Life-Cycles


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